Technologies are being developed for capturing carbon dioxide (CO2) from industrial gas streams to reduce energy costs and the environmental impact of CO2 in the atmosphere. Major sources of CO2 emissions include power plants, cement kilns, natural gas processing facilities, ammonia plants, and hydrogen plants. The captured CO2 can be sequestered or can be reutilized for: enhanced oil recovery, food processing or accelerated algae growth that could have multiple applications. In the cases of natural gas processing and ammonia production, removal of CO2 is necessary step to meet product specifications. In the case of industrial hydrogen production, CO2 removal can improve plant efficiency and increase product output.
Currently several alternate CO2 capture technologies are in various stages of commercial practice and development. These include chemical absorption using amine solvents (particularly monoethanolamine—MEA), physical adsorption, membrane separation, cryogenic distillation, and mineral carbonation Chemical absorption with amines is currently considered the lowest cost method of CO2 removal for the majority of gas streams, particularly for the clean-up of low levels of CO2 in natural gas. MEA systems are more reactive, and therefore preferred, but the energy requirements to remove the absorbed CO2 from the MEA is very high, at about 4 million BTU/tonne of CO2 and can require up to about one-third of a power plant's boiler output.
One emerging alternative to amine stripping is to incorporate biocatalysts that are specific for carbon dioxide conversion (CO2) in the presence of low duty solvents, subsequently lowering the regeneration energy requirements and lowering overall cost. Carbonic anhydrases (CAs), EC 4.2.1.1, are a family of enzymes that are ubiquitous in nature and are known to reversibly convert bicarbonate into CO2 and water catalytically.
There is a need in the art for improved materials, compositions, methods, processes, and systems which improve the stability and efficiency of enzymes for use in the catalysis of industrial processes.